Weirdly withering plums

Many of the ripening plums on my tree have been withering - discoloured (pale and mottled) and shrivelled, lengthening until they almost resemble laburnum pods. Yet their neighbours appear fine. The symptoms don't fit those of any disease of plum trees that I can find online.

Any ideas for what's causing this and how to treat/stop it? This was the first good crop the tree's had for some years.

Thanks. Aside from the mention of swelling on one side (which I haven't seen in dozens of affected fruits), the Wikipedia description of this sounded very much like the problem I've got. The RHS (whose site I finally remembered to check specifically) only called this 'pocket plum' - confusingly different from the American 'plum pockets' apparently caused by Taphrina communis. Clearly it's a developing science!

Already? It's much earlier in the year than I found it happening to my plum tree....

I cut off all the affected twigs etc, in hopes of preventing any spread to previously unaffected fruit, but didn't have much fruit in the end. Hoping for better luck this year, since the blossom has been quite lush and we haven't had high winds etc to knock it down.

You could check Wikipedia and the RHS site information about this in case there are any chemical treatments which, as an organic gardener, I wouldn't have tried.

Thanks for that. Appreciate the update. Our plum trees are huge (as tall as the house) so it's not going to be possible for me to cut off the branches etc. so I have no idea what I'm going to do... Good luck this year!

This is entirely different from the problem I had. The affected fruits on my plum tree lost all their usual colour and texture, withering away to something long, thin and distorted as well as completely discoloured. The absence of any stone (what you called a pip) inside the fruit was purely incidental to the failure to mature normally.

My experience is that a plum tree can go for several years without bearing any fruit (or only very little) after producing a really heavy crop one year. They need time to regain their strength, apparently.

My plum tree has got the same problem again - and there are healthy plums growing on the same twigs as affected ones, so cutting out the bad growth is going to be fiddly and unlikely to eradicate the parts of the tree that are obviously infected. I'll have to mark what bits to prune off later in the year.

OK - I think I can positively identify this for you as I've been trying to bring this under control on my own plum trees and damsons - you have pocket plum. It is closely related to plum leaf curl and you'll often see the two together (although not always). Symptoms include swollen and distorted plums that grow more rapidly in size than normal plums and lack a stone. These infected plums then develop a mildewy coating which infects other plums and so on.

It's a fungal disease. The best control I have found is removal of the affected branches and plums before they develop the mildewy coating and then a spray of bordeaux solution (copper sulphate + slaked lime) twice during dormancy (once in autumn and once before the buds open is spring).

There are some other chemical controls (Westland plant rescue, microbutinol etc.) but bordeaux is really the best solution (snigger) and is organic too

Thanks - I'd identified the problem but hadn't realised that there was an organic remedy. Where do you get Bordeaux solution (or the ingredients for it)?

I haven't seen the mildew on my tree - maybe I cut off the affected fruit etc early enough last year that it didn't have time to develop - but clearly just taking off the affected twigs during the summer isn't enough to prevent recurrence.

On searching further, I was slightly unnerved to find someone quoting the RHS website as saying that,"Bordeaux Mixture will be withdrawn from sale on 28 February 2013 but any person can use and store existing stocks until 28 February 2015." Can't find that on that site now, though.

I wouldn't lisyen to the RHS TBH - Bordeaux mixture has been used for years on Pocket Plum and is a standard treatment across the world. Certainly it's been the norm on most farms for as long as I can remember.

Plus it'll be very, very hard to withdraw Bordeaux from sale as no one I know actually buys it "made up" as it is too expensive and simply doesn't keep. Make it up yourself by buying slaked lime and copper sulphate from a chemical supplier or ebay. Bear in mind that made up this traditional way it needs to be used on the day. You'll find plenty of recipes online for it.

"On searching further, I was slightly unnerved to find someone quoting the RHS website as saying that,"Bordeaux Mixture will be withdrawn from sale on 28 February 2013 but any person can use and store existing stocks until 28 February 2015."

I was so surprised about that RHS guidance I thought I'd look that up and see what they said. Their main page on Pocket Plum actually recommends using Bordeaux so it seems that the original poster may have that confused with another fungicide!